Error setting json value to null

You cannot set a nullable json value to null

**To Reproduce**
define a json column in the prisma schema like this:
```prisma
model MyTable {
id String @id @db.Uuid
myColumn Json?
}
```
then build graphql schema and execute the following mutation
```graphql
mutation {
updateMyTable(data: { myColumn: null},
where: {id: "3e48e900-20f3-4cce-899e-f6323525645d"}) {
id
myColumn
}
}
```

**Expected Behavior**
The value should be updated to null

**Logs**
```
[GraphQLError [Object]:
Invalid `helpers_1.getPrismaFromContext)(ctx).myTable.update()` invocation in
/node_modules/@generated/type-graphql/resolvers/crud/MyTable/MyTableCrudResolver.js:69:68

66 }
67 async updateMyTable(ctx, info, args) {
68 const { _count } = (0, helpers_1.transformFields)((0, graphql_fields_1.default)(info));
→ 69 return (0, helpers_1.getPrismaFromContext)(ctx).myTable.update({
where: {
id: '3e48e900-20f3-4cce-899e-f6323525645d'
},
data: {
myColumn: null
~~~~
}
})

Argument myColumn for data.myColumn must not be null. Please use undefined instead.

] {
locations: [ { line: 2, column: 3 } ],
path: [ 'updateMyTable' ],
extensions: {
requestId: '97562b3c-d5ad-4a1d-b944-3fb9f9729e82',
code: 'INTERNAL_SERVER_ERROR'
}
}
```

Package versions:
prisma@3.7.0
typegraphql-prisma@0.18.3
type-graphql@1.1.1

Reproduce the mutation against the Prisma schema and inspect the generated update resolver at node_modules/@generated/type-graphql/resolvers/crud/MyTable/MyTableCrudResolver.js:69. Trace how the nullable Json field reaches myTable.update, then verify that executing the mutation stores null without the reported validation error.

Written by the indexing model from the issue text.